Big Muff tone continuity

[yeeshkul]

Just finished a Big Muff clone and noticed the sound does not have very continuous sustain when i play bass chords. The treble tones are fine. Is that normal? Just checked it out with the audio-probe, and the quality gets worse on the 2-3 stage. Can that be caused by the elyte caps? (I used elytes in feedbacks and input/output, also various trannies in sockets). Otherwise it sounds nice. I used BC550C for Q1 and SmallBears 2N5133 (Hfe ~ 150-200).

[blueduck577]

try fiddling with the capactiors that are in series with the diodes in the feedback loop.  you didn't specify which schematic or version you are working off of, but try 1uF and work up from there if you still need more bass clipping.

[oliphaunt]

I have found that the caps in series with the diodes in the feedback loops need to come between the diodes and the 9v supply or you get a fizzly sounding decay to the notes.  I have seen schematics with the caps in both positions.  I don't know if that's a mistake, but switching them solved my decay problems.

[Nitefly182]

There is a good chance that those 2n5133 are under 100hfe. Did you check them?

[oliphaunt]

There is a good chance that those 2n5133 are under 100hfe. Did you check them?

I recently built 2 Ram's Head Muffs with those 2n5133, several of which tested around 70 hfe, average 150. I thought they sounded great, very smooth and warm, I much prefer them to higher gain transistors like 5088.  Once I got the feedback loop cap issue solved everything was smooth sailing.

[yeeshkul]

The 4 2N5133 trannies are about 150-200 Hfe. I tried various transistors - they have no impact on the bass sustain. These are fine, i like the sound and it has enough drive for my purposes -> the gain (beta) of the gain stages is still below their Hfe anyway... the gainy trannies sound just sharper, i don't like it too much.
As i say - the treble notes are perfect, just when i hit E+A string, playing G->A for example, the sustain dies faster than i would expect and it is not smooth. That's why i am suspecting the elyte caps, because they may have troubles with the bass content. I may try polyester for 1u...

I built something like Ram's head, although it is not easy to say, i have seen Ram's that were quite like triangle and vice versa. Yes i used 1u elyte caps in the feedbacks and they are on the DC branch. Also i used 10u input elyte cap and 1u output elyte cap to get some nice bass response, don't wanna squeaky Muff .
Decoupling caps are 100u polyester.

DC bias seems to be fine, around 4-5V on all collectors.
Did anyone experience similar sustain problems?
I used the audio-probe to get sound from particular collectors
- 1st stage ok, clean sound
- 2nd stage - ok, nice overdrive, smooth sustain
- 3&4the stage - Mufffffff but sustain at bass notes dies too fast

By the way you can hear Gilmour's triangle muff here: http://www.kitrae.net/music/big_muff_history.html#TriangleBigMuff
it does the same thing like mine (just all around the neck) ... maestro must have been a bit unhappy with that, he normally doesn't play out of tune at all.